Photocatalytic degradation of Reactive Blue 21 from aqueous solutions using Zinc oxide

Dyes are extensively used in the different industry during dyeing process and the excess dyes are released into the effluent streams as waste after coloring [1]. The released wastes including dyeing are toxic and must be removed from environment [2]. Most of synthetic dyes are resistance to conventional degradation methods [3]. Semiconductor photo catalysis is one of method that has great potential to degradation of aqueous pollutants [4]. In this research Reactive Blue 21 is chosen as a model dye and photo degradation of it was investigated by using the ultraviolet in presence and absence of zinc dioxide. The advantage of using semiconductor in degradation of dye is the mineralization of dyes, without generation of waste [5]. It has been found that the increasing of ZnO dosage and ultra violet intensity due to increase in photo degradation of Reactive Blue 21 dye. Also, more degradation was occurred in basic solution than acidic solutions. The activation energy of photo degradation processes was calculated in the range of 298, 308 and 338 K and was obtained 39.65, 34.65 and 32.54 kJ/mol, respectively.